<!DOCTYPE html>
<html lang="en" xmlns:v-on="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Vue 实例</title>
    <script src="vue.js"></script>
</head>
<body>
    <div id="app">
        <p>{{ foo }}</p>
        <!-- 这里的 `foo` 不会更新！ -->
        <button v-on:click="foo = 'bazzzzzz'">Change it</button>
    </div>

    <script>
        var obj = {
            foo: 'bar'
        }

        // Object.freeze(obj)

        new Vue({
            el: '#app',
            data: obj
        })
    </script>
</body>
</html>